Patent GB-662831-A (GB)
Title: Automatic pilot
IPC: G05D1/08
Filed: 1944-11-17
Abstract: 662,831. Electric control systems. BENDIX AVIATION CORPORATION. Nov. 17, 1944. [Dec. 31, 1943] No. 22906/44. Class 40 (i). [Also in Group XXXV] In a system for automatically controlling an aircraft about one of its axes by means of a servomotor operated control surface, a disconnectible driving connection is provided between the servomotor and the control surface and the servomotor is controlled, whether connected to the control surface or not, by a combination of two electrical signals, one generated on deviation of the craft from a predetermined attitude and one generated in response to operation of the servomotor. In Fig. 2 a rudder 22 is automatically controlled by an earth inductor compass 10 and a rate-of-turn gyro 184 to maintain a craft on a predetermined course. Primary windings 35, 36 of the compass are energised from an A.C. source while secondary windings 37, which produce a signal at double the supply frequency on deviation of the craft from course, are connected to the stator 42 of an inductive device 43. The resulting signal from rotor 49 of this device controls, through an amplifier 16, one phase of a two-phase induction motor 57 the other phase 55 of which is coupled to the A.C. source through a frequency doubler 56. Motor 57 which is coupled through reduction gearing 60 to rotor 49 to provide mechanical follow-up, drives, in response to a deviation signal and through a magnetic clutch 87, the rotor 83 of an inductive transmitter, the stator 82 of which is connected to the A.C. source. Rotor 83 thus produces a signal which is applied to a thermionic valve amplifier 18, which includes saturable reactors; Fig. 4 (not shown), supplying, through a control panel 20, one phase of a two-phase induction motor 102. Motor 102 which operates rudder 22 through gearing and a magnetic clutch 146 to correct the deviation also drives, through reduction gearing 176, the rotor 173 of an inductive device 171. The stator 172 of this device is supplied from the A.C. source and the rotor produces an electrical follow-up signal which is applied through control panel 20 to amplifier 18. During turn of the craft rate-of-turn gyro 184 moves rotor 192 of an inductive transmitter 190. This rotor is supplied from the A.C. source and the stator is connected to the stator of an inductive receiver 201 the rotor 202 of which produces an electrical signal proportional to the rate of turn of the craft which is applied through control panel 20 to amplifier 18. The relative magnitude of the various signals applied to amplifier 18 may be adjusted manually by means of potentiometers (not shown) on control panel 20. Magnetic clutches 87 and 146 are energised from a battery 29 when switches 92 and 93 are closed manually. Depression of push button 401 releases switch 92 electromagnetically for manual steering. Under these conditions a device including a pin 100, levers 95 and 97 and a spring 98 ensures the return of rotor 83 to a position of zero signal in readiness for future automatic operation. A scale 62 co-operating with a fixed pointer 64 is driven by rotor 49 to indicate the heading or deviation from course of the craft. This scale is given an additional movement, to compensate for compass error, through a worm 70 from an arm 74 carrying a follower 73 of cam plate 71, the shape of which is adjusted by screws 72 during a swing of the craft. Rate-of-turn is also indicated by pointer 197. An inductive transmitter 75 the rotor of which is driven with course indicator 62 provides an electrical signal for operating remote repeaters. Substitution of a radio compass for the earth inductor compass is referred to. In Fig. 3 (not shown), to maintain a predetermined altitude and attitude of the craft, other servo-mechanisms of the type shown in Fig. 2 control the, elevators and ailerons respectively in response to signals transmitted through separate thermionic amplifiers from inductive pick-offs associated with perpendicular axes, corresponding to the craft's pitch and bank axes, of an artificial horizon gyro. Operation of push button 401 releases magnetic clutches to disengage these controls also. Signals proportional to the rate of pitch or bank may be introduced into the amplifiers if required. Utilisation of the gyro-vertical supporting the earth inductor compass in place of the artificial horizon gyro is referred to. Specifications 550,399, 550,779, 565,277, 592,394, [Group XXXVI], 662,833, 662,854 and 662,855, [all in Group XXXV], are referred to.